Strength grades of bolts are mainly divided into the following grades: 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc.
Bolts of different strength grades and their application scenarios
3.6, 4.6, 4.8, 5.6 grade bolts: These grades of bolts are ordinary bolts, mainly used in light or medium load occasions, such as some low-requirement equipment and parts.
6.8 grade bolts: With high strength and toughness, they are suitable for the installation and maintenance of heavy equipment, and are often used in machinery manufacturing, automotive industry and other fields.
8.8 grade bolts: They are high-strength bolts with a tensile strength of 800MPa and a yield strength of 640MPa. They are widely used in heavy machinery and equipment, construction engineering and other fields.
9.8 grade bolts: Although there is less specific information, they usually belong to the category of high-strength bolts and are suitable for connections that require higher strength.
10.9 grade bolts: ultra-high strength bolts with a tensile strength of 1000MPa, suitable for high-demand occasions such as steel structure connections of large steel structure bridges and high-rise buildings.
12.9 grade bolts: top-strength bolts with a tensile strength of up to 1200MPa, mainly used in special engineering fields such as aerospace and military equipment, which have extremely high requirements for the strength, precision and reliability of bolts.
Bolt materials and manufacturing processes of different strength grades
Ordinary bolts (below grade 8.8): usually made of carbon steel and do not require heat treatment.
High-strength bolts (grade 8.8 and above): generally made of low-carbon alloy steel or medium-carbon steel, and heat treated (quenching, tempering) to increase strength.
Examples of the application of bolts of different strength grades in engineering
8.8 grade bolts: widely used in machinery manufacturing, automobile industry, construction engineering and other fields, such as engine connection, bridge structure and other important parts.
10.9 grade bolts: Mainly used for large steel structure bridges, steel structure connections of high-rise buildings, heavy machinery and equipment, etc.
12.9 grade bolts: Mainly used in aerospace, military equipment and other fields with extremely high strength requirements.
